CKMath Unit 7: Adding and Subtracting within 1,000
Focus:
In this unit, students add and subtract within 1,000, with and without composing and decomposing a base-ten unit. They apply the methods they know and their understanding of place value and three-digit numbers to find sums and differences within 1,000. Initially, students add and subtract without composing or decomposing a ten or hundred. Instead, they rely on methods based on the relationship between addition and subtraction and the properties of operations. They make sense of sums and differences using counting sequences, number relationships, and representations (number line, base-ten blocks, base-ten diagrams, and equations). As the unit progresses, students work with numbers that prompt them to compose and decompose one or more units, eliciting strategies based on place value. Students learn to recognize when composition or decomposition is a useful strategy when adding or subtracting by place. In the later half of the unit, they encounter lessons that encourage them to think flexibly and use strategies that make sense to them based on number relationships, properties of operations, and the relationship between addition and subtraction.
Number of Lessons: 14 and 4 optional
Instruction Time:
Approximately 60 minutes
(Please note that each lesson is designed for one instructional block, and may be divided into shorter or longer segments based on teacher pacing and student needs.)
Additional Search Terms:
attributes • properties of operations • number line • base-ten diagrams • equations
